1. Field of the Invention
A method of separating young blood platelets from a mixture of young and old blood platelets is disclosed. The method comprises adding a lectin under nonactivating conditions to a mixture of young and old blood platelets and allowing agglutination. The agglutinated young blood platelets may be isolated from the older blood platelets and then separated from the lectin. This results in a composition consisting essentially of young blood platelets.
2. Description of the Prior Art
Platelets are small cells in human or animal blood which are essential for the clotting of blood. Platelets in circulation in the body are a heterogeneous mixture of platelets of different ages. Platelets are very fragile and when stored in a blood bank are usually discarded after approximately 4 days because of age. Age becomes apparent because of the loss of platelet functionality and metabolic capabilities. Further, when platelets are used from a blood bank only about one half of the platelets survive in circulation. As mentioned, it is known that younger platelets have higher metabolic and functional capabilities as compared to older platelets. In addition to the above mentioned advantages, younger platelets have a longer shelf life than currently used blood platelet mixtures which contain both young and old blood platelets. Therefore, a need arose to devise a gentle method of selectively isolating the younger platelets from a platelet mixture of different ages.
Ganguly et al; Biochem. Biophys. Res. Comm., 1979, 89(4), 1154-1160, discloses that wheat germ agglutinin binds to the surface of human platelets and leads to their agglutination. Wheat germ agglutinin caused clumping of fresh platelets. It is further disclosed that in washed human platelets, wheat germ agglutinin is known to bind to surface glycoproteins and thereby induce cell agglutination.
Chemical Abstracts 92: 56730e discloses that three lectins separated from UIex europius, Ricinus communis, and Glycine max (soybean) induce aggregation of human platelets.
Greenberg et al; Biochim. Biophys. Acta, 1974, 345, 231-242 discloses that out of nine lectins studied, wheat germ agglutinin was the most effective towards platelet aggregation.
Naim et al; Thrombosis Res., 1982, 26, 431-441 discloses that lectins are useful for the isolation of glycoproteins because they have pronounced affinities for certain sugars.
Lectins are known to cause human blood platelet agglutination (aggregation) by binding to surface glycoproteins. Wheat germ agglutinin is especially known to be an effective agglutinator. Lectins are also used to isolate glycoproteins because of their affinity for specific sugars. However, the instant invention is novel and certainly an advancement in the art in that (1) lectins are used to separate platelets depending on the number of surface sugars present and (2) blood platelets have fewer surface sugars as the platelets become older. Therefore, in the instant invention young blood platelets are obtained by adding to a mixture of blood platelets at least one lectin; allowing the blood platelet mixture containing the lectin to agglutinate; isolating the agglutinated product and then removing the lectin from the agglutinated product resulting in a composition consisting essentially of young blood platelets.